In the dozen or so decades since their appearance, bicycles have become one of the most ubiquitous machines on earth, being used by many millions around the world as a reliable and inexpensive means of transportation. Bicycles, and variations on the traditional two-wheel upright bicycle such as recumbent bicycles, tandem bicycles, tricycles, and electric bicycles, are typically much cheaper than automobiles, yet can be used to travel distances sufficient to make the bicycle a satisfactory means of commuting, traveling to and from school, shopping, and performing many other tasks.
However, bicycles are not without drawbacks. Bicycles must often be ridden on roads intended for trucks and automobiles, and in such situations a bicycle rider is exposed to constant danger. Hence, there is the problem with conventional bicycles that the rider often must ride alongside trucks and automobiles, and is in danger of being struck by and even seriously injured or killed by such vehicles.
Also, bicycles are ill-suited to adverse road conditions, and cannot conveniently, easily or safely be used where the ground is covered with snow and ice, deep mud, debris with sharp edges such as broken glass, or obstructions such as rocks or branches. Thus, conventional bicycles have the problem that travel on surfaces under such adverse conditions is often inconvenient, difficult, or unsafe.
Moreover, because the tires of a bicycle travel over road and other surfaces which are often rough and uneven, the rider must often use excessive force when pedaling to propel the bicycle forward. Thus, there is the further problem of human-powered bicycles of the prior art that considerable exertion is sometimes necessary to travel over rough or uneven roads or terrain.
Moreover, when riding a bicycle on a sidewalk, or on an edge of a street, or on various other routes, various obstructions may oblige the rider to ride slowly or to brake often. Hence, there is the further problem with conventional bicycles that the speed with which the bicycle can be ridden is often much slower than would be attainable in the absence of obstructions.
Moreover, bicycles can as a rule only be ridden on reasonably flat surfaces. Hence, there is the further problem with conventional bicycles that some obstructions, such as low fences, streams, flower beds, guardrails, and the like, cannot be traversed at all.
Also, when urban designers undertake to construct a bicycle path or other space specifically for bicycle riders, in order to mitigate some of the above problems such as the problem of safety, there occurs the further problem that space in urban environments is scarce and valuable, so that often only a very limited amount of space can be dedicated solely to bicyclists.
In addition, when bicycles share space on roads with trucks and automobiles, congestion often results, due to the coexistence of different modes of transportation, with their different modes of behavior. Hence, there is the further problem that bicycle use on roadways intended for vehicular traffic often results in traffic congestion.
In U.S. Pat. No. 638,822 and U.S. Pat. No. 693,128, bicycles are disclosed which have been extensively modified to enable travel on the two rails of ordinary railroad tracks, with three arms extending from one side of the bicycle and supported by a wheel which rests on one rail, while the two wheels of the bicycle are modified to enable travel on the other rail. However, in addition to being limited only to travel on railroad tracks, such modified bicycles have the disadvantage of requiring extensive modifications using long and cumbersome members which could not easily be attached and detached or carried. Similar modified bicycles with less cumbersome modifications have been disclosed, as in for example U.S. Pat. No. 5,461,984, but travel is again limited to railroad tracks.
In for example U.S. Pat. No. 563,793, incorporated by reference herein, an aerial bicycle is disclosed which is designed to be hung from an elevated track and ridden. Such an apparatus enables travel elevated above the ground, but the aerial bicycle disclosed is a dedicated vehicle which can only be used in conjunction with the elevated track described. Other bicycles intended for use on a purpose-built elevated track but which cannot be used, or cannot easily be used, as ordinary bicycles are for example disclosed in U.S. Pat. No. 550,878, U.S. Pat. No. 488,200, U.S. Pat. No. 844,116, U.S. Pat. No. 526,832, and U.S. Pat. No. 600,371, all of which are incorporated by reference.
There have also been disclosed elevated paths or roads intended specifically for bicycles, as for example in U.S. Pat. No. 4,649,588; but such structures, while enabling elevated travel using ordinary bicycles, are comparatively large and expensive, and typically provide no means for guiding bicycles and riders on a narrow path.
U.S. Pat. No. 638,296 discloses a bicycle trolley car, in which a bicycle is used in an elevated mode, riding along an overhead trolley wire or rail, and propelled by the rider.
U.S. Patent Application Publication No. 20060284389 discloses a tracked bicycle, which has been converted for use on snow, sand, mud, or similar. However, the conversion process is attended with difficulty, and such a vehicle remains on the ground, and so subject to difficulties presented by such as uneven terrain and large obstructions.
U.S. Pat. No. 599,697 discloses a human-powered vehicle which can be ridden either on the ground, or suspended from an overhead track, thereby resolving a number of the problems of the prior art noted above.
The present invention was devised in light of the above problems, and has as an object the provision of a system of transportation employing bicycles which secures greater safety for the bicycle rider, while not impeding use of the bicycle as an ordinary bicycle.